Ventilation fan

• US 6,386,828 B1
• Filed: 01/03/2001
• Issued: 05/14/2002
• Est. Priority Date: 01/03/2000
• Status: Expired due to Term

• Current Assignee: Munters Corporation
• Original Assignee: Aerotech, Inc. (Munters Corporation)
• Inventors: Davis, James R., Hansen, Daniel G.
• Primary Examiner(s): Joyce, Harold
• Application Number:
  US09/753,405
• Time in Patent Office: 496 Days
• Field of Search: 415/146, 415/147, 454/353, 454/259, 416/223.R, 416/228, 416/237
• US Class Current: 415/147
• CPC Class Codes: A01K 1/0052 Arrangement of fans or blowers
• CPC Class Codes: A01K 1/0064 Construction of air inlets or outlets in walls
• CPC Class Codes: F04D 25/14 and having shutters, e.g. automatically closed when not in use
• CPC Class Codes: F24F 7/013 using wall or window fans, displacing air through the wall or window
• CPC Class Codes: Y10T 137/7839 Dividing and recombining in a single flow path

Abstract

A ventilation fan assembly (10) having a fan (22) mounted in a housing (12) and a shutter assembly (60). The housing has a square inlet portion (12C), a circular center portion (12E) and a conical outlet portion (12D) having rifling grooves (20). The shoulder (16) formed between the inlet portion and the center portion is radiused to reduce disruption of air flowing from the inlet portion to the center portion. The shape of the blades (32) of the propeller (28) is such that the axial velocity produced as the propeller rotates is essentially constant along the length of the blades. The shutter assembly has a large, radiused entrance and airfoil shaped blades which reduce air disruption. The blades have a flexible flap (68) along the trailing edges (64D) which form a seal between adjacent blades to prevent air from leaking from the housing through the shutter assembly.

Claims

1. A fan assembly for use in ventilation of a building, which comprises:

(a) a housing having an outlet with a conical shape and an inlet with an inner cavity extending between the inlet and the outlet, the inner cavity having a center portion with a circular cross-section;

(b) a bracket mounted in the inner cavity of the housing spaced between the inlet and the center portion; and

(c) a fan mounted on the bracket and having a motor connected to a shaft with a propeller mounted on one end of the shaft, the fan being mounted on the bracket such that the propeller is spaced apart from the inlet and the outlet of the housing, the propeller having blades, each blade having a shape such that when the propeller is rotating, an axial velocity of air coming off the propeller is essentially constant along most of a length of the blades from a tip of the blades toward the shaft wherein the blades of the propeller are located in the center portion of the inner cavity spaced apart from the inlet of the housing.

2. The fan assembly of claim 1 wherein the inlet of the housing has a square cross-section.

3. The fan assembly of claim 2 wherein a shoulder is formed in the inner cavity of the housing at an intersection of the inlet and the center portion and wherein the shoulder is rounded such as to reduce disruption of air entering the center portion from the inlet.

4. The fan assembly of claim 1 wherein the bracket is mounted adjacent the center portion and wherein the fan is mounted on the bracket such that the propeller is completely within the center portion of the inner cavity.

5. The fan assembly of claim 4 wherein the length of the blades is such that a distance between the center portion of the housing and the tip of each blade is between 0.4% and 0.8% of a diameter of a path of the propeller.

6. The fan assembly of claim 1 wherein the bracket includes a first and second arm which extend across the inner cavity of the housing such that the shaft of the fan is co-axial with an axial center of the center portion of the inner cavity.

7. The fan assembly of claim 6 wherein the first and second arms have opposed ends with a front side extending between the ends and wherein the arms are mounted in the inner cavity such that the front side is facing the inlet of the housing and wherein the front side of the first and second arms of the bracket is radiused to reduce disruption of air entering the center portion from the inlet.

8. The fan assembly of claim 6 wherein the first and second arms of the bracket each include opposed end sections with a center section spaced therebetween wherein the end sections extend outward from the center section such that when the bracket is mounted in the inner cavity, planes formed by the arms extend through and intersect at the axial center of the center portion of the inner cavity.

9. The fan assembly of claim 1 wherein the housing has grooves adjacent the inner cavity extending at an angle between the center portion of the inner cavity and the outlet of the housing.

10. The fan assembly of claim 9 wherein the grooves are evenly spaced around the housing.

11. The fan assembly of claim 9 wherein the outlet of the housing is a discharge cone having a conical shape and wherein the grooves are angled in a clockwise direction around the discharge cone.

12. The fan assembly of claim 1 wherein a backdraft assembly is mounted at the inlet of the housing, wherein the backdraft assembly includes a frame with shutter blades pivotably mounted on the frame, wherein the shutter blades have an airfoil shape with a leading edge and a trailing edge and are mounted at the leading edge to the frame and wherein a flexible flap is mounted on the trailing edge such that when the shutter blades are in a closed position, the flexible flap of one shutter blade contacts a next adjacent shutter blade for sealing the backdraft assembly to prevent air in the inner cavity of the housing from moving out of the housing through the inlet and the backdraft assembly and wherein a side of the frame opposite the inlet is radiused to reduce disruption of air entering the fan assembly.

13. The fan assembly of claim 12 wherein the frame has a first rail and a second rail with opposed first and second side rails and a center rail extending between the first and second rails wherein first shutter blades extend between the first side rail and the center rail and second shutter blades extend between the second side rail and the center rail such that the first shutter blades pivot independently of the second shutter blades.

14. The fan assembly of claim 12 wherein the backdraft assembly is removable and wherein the inner cavity of the housing adjacent the inlet is provided with toggle latches which engage a strike mounted on the frame of the backdraft assembly to secure the backdraft assembly on the inlet.

15. The fan assembly of claim 1 wherein the propeller has a center hub with a first end and a second end and is mounted on the shaft such that the first end is facing the outlet of the housing and the second end is facing the inlet of the housing, wherein the blades have opposed first and second ends with first and second sides extending between the ends and are mounted on the center hub at the first end such that the first side is adjacent the first end of the hub and the second side is adjacent the second end of the hub wherein the first side of the blades adjacent the first end has a rounded protrusion which assists in keeping the axial velocity of the air coming off of the propeller constant along most of the length of the blades.

16. The fan assembly of claim 15 wherein a width of the blades between the sides adjacent the first end is less than a width of the blades between the sides adjacent the second end.

17. The fan assembly of claim 1 wherein the propeller has three blades.

18. A fan assembly for use in a building for ventilation, which comprises:

(a) a housing having an outlet with a conical shape and an inlet having a square cross-section with an inner cavity extending between the inlet and the outlet, the inner cavity having a center portion with a circular cross-section;

(b) a fan mounted in the housing between the inlet and the outlet and having a motor connected to a shaft with a propeller mounted on one end of the shaft, the propeller having blades wherein the fan is mounted in the housing such that the propeller is spaced apart from the inlet and the outlet of the housing; and

(c) a backdraft assembly mounted on the inlet of the housing and having a frame with shutter blades pivotably mounted on the frame and extending horizontally across the inlet of the housing wherein the shutter blades have an airfoil shape with a front edge and a rear edge and are mounted at the front edge to the frame wherein a flexible flap is mounted on the rear edge wherein when the shutter blades are in a closed position, the flexible flap allows for sealing of the shutter blades to prevent air in the inner cavity of the housing from moving out of the housing through the inlet and the backdraft assembly.

19. The fan assembly of claim 18 wherein the frame of the backdraft assembly has radiused edges on an outside surface opposite the inlet of the housing to reduce disruption of air entering the housing.

20. The fan assembly of claim 18 wherein each blade of the propeller is configured such that when the propeller rotates, an axial velocity of air coming off the propeller is essentially constant along most of a length of the blades from a tip of the blades to the shaft.

21. The fan assembly of claim 18 wherein a bracket is mounted in the inner cavity of the housing spaced between the inlet and the center portion adjacent the center portion and wherein the fan is mounted on the bracket such that the propeller is completely within the center portion of the inner cavity of the housing.

22. The fan assembly of claim 21 wherein the bracket includes a first and second arm which extend across the inner cavity of the housing such that the shaft of the fan is co-axial with an axial center of the center portion of the inner cavity.

23. The fan assembly of claim 22 wherein the first and second arms have opposed ends with a front side extending between the ends wherein the arms are mounted in the inner cavity such that the front side is facing the inlet of the housing and wherein the front side of the first and second arms of the bracket is radiused to reduce disruption of air entering the center portion from the inlet.

24. The fan assembly of claim 22 wherein the first and second arms of the bracket each include opposed end sections with a center section spaced therebetween wherein the end sections extend outward from the center section such that when the bracket is mounted in the inner cavity, planes formed by the arms extend through and intersect at the axial center of the center portion of the inner cavity.

25. The fan assembly of claim 18 wherein the housing has grooves adjacent the inner cavity extending at an angle between the center portion of the inner cavity and the outlet of the housing.

26. The fan assembly of claim 25 wherein the grooves are evenly spaced around the housing.

27. The fan assembly of claim 25 wherein the outlet of the housing is a discharge cone and wherein the grooves are angled in a clockwise direction around the discharge cone.

28. The fan assembly of claim 18 wherein the frame of the backdraft assembly has a first rail and a second rail with opposed first and second side rails and a center rail extending between the first and second rails wherein first shutter blades extend between the first side rail and the center rail and second shutter blades extend between the second side rail and the center rail such that the first shutter blades pivot independently of the second shutter blades.

29. The fan assembly of claim 18 wherein the backdraft assembly is removable and wherein the inner cavity of the housing adjacent the inlet is provided with toggle latches which engage a strike mounted on the frame of the backdraft assembly to secure the backdraft assembly on the inlet.

30. The fan assembly of claim 18 wherein the propeller has a center hub with a first end and a second end and is mounted on the shaft such that the first end is facing the outlet of the housing and the second end is facing the inlet of the housing, wherein the blades have opposed first and second ends with first and second sides extending between the ends and are mounted on the center hub at the first end such that the first side is adjacent the first end of the hub and the second side is adjacent the second end of the hub wherein the first side of the blades adjacent the first end has a rounded protrusion which assists in keeping the axial velocity of the air coming off of the propeller constant along most of the length of the blades.

31. The fan assembly of claim 30 wherein a width of the blades between the sides adjacent the first end is less than a width of the blades between the sides adjacent the second end.